The invention concerns machines for filling containers.
More particularly, it concerns container filling machines having at least one fill station provided with a sealed enclosure intended to receive at least one container to be filled. In this type of machine, the enclosure is opened to allow the container to be loaded or removed, and it is closed again to allow the atmosphere in the enclosure to be controlled while the container is being filled. The enclosure is delimited by a top wall into which a fill nozzle opens, an appreciably cylindrical side wall, and a bottom wall.
For example, such a machine is described in Patent Application WO-99/05061. In particular, it allows containers to be filled with products that need to be drawn off under special conditions of pressure.
In the food industry, it is known that some beverages, such as beer, must be drawn off under a pressure that is lower than the atmospheric pressure, while others, such as carbonated drinks, are preferably drawn off under a pressure that is greater than the atmospheric pressure.
Machines having enclosures with controlled atmosphere, by adapting the pressure inside the sealed enclosure, make it possible to limit and even nullify the difference in pressure between the inside and outside of the container being filled. This is particularly useful to allow the filling of containers made of thermoplastic material obtained by blow-molding, especially if they are manufactured just prior to being filled and are taken to the filling machine before their temperature has completely stabilized.
A purpose of the invention is to propose a new design of such a machine, and particularly a new design of fill enclosures to make it possible to decrease the manufacturing cost and the operating cost, and at the same time permit optimal operation of the machine with containers of variable size.
To that end, the invention proposes a filling machine of the type described above, characterized in that the machine has means to modify the volume of the closed enclosure.
According to other characteristics of the invention:
the form of an interchangeable part, and the fill station is able to receive different bottom walls to change the volume of the closed enclosure;
the opening and closing of the enclosure are achieved by the axial sliding of the side wall, the bottom wall remaining immobile;
the axial position of the bottom wall is adjustable in order to change the volume of the closed enclosure;
the bottom wall has a regulation port that opens into the enclosure and through which regulation port the atmosphere of the enclosure is controlled;
the bottom wall is mounted on a base on which it rests axially downward when the enclosure is open; the bottom wall is mounted on the base with an axial clearance, and when the enclosure is closed, the bottom wall is axially resting downward against one support surface connected to the side wall;
the base of the bottom wall has an axial tubular shaft, the upper end of which has a base plate on which the bottom wall can rest when the enclosure is open; the regulation port of the bottom wall is connected by a regulation conduit 46 to a connector integral with the lower end of the tubular shaft, and the regulation conduit is received inside the tubular shaft;
the regulation conduit is composed of a rigid pipe that is axially integral with the bottom wall and which is mounted with an axial clearance inside the tubular shaft;
the side wall has a lower bearing that is slidably mounted on the tubular shaft to guide the side wall between a lower open position and an upper closed position;
the fill station has locking means that allow the side wall to be axially locked on the fill head when the enclosure is closed;
the side wall is composed of two parts which, when the enclosure is opened or closed, move in opposite directions; and
the fill station has means for supporting the container that are movable between at least a loading position and a fill position in which the interior of the container is isolated from the interior of the enclosure.